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Tony
Cook imaged this flash from the island of Tenerife  on
October 24, '04. The sun is setting behind clouds. Tony was
some 20-30ft above sea level and saw three green flashes during
the one sunset. The flash is a variant of an M-Mir type produced by
the miraging and magnifying effects of a vertically wavy inversion
layer. The
'smudge' to the left is the mirage distorted giant sunspot group
#687. More ↓
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The
inversion layer in this case cannot be at constant height
above the earth's surface because the flash is above the
astronomical
horizon. The layers here (there are several)
are likely shaped by vertical waves in the atmosphere.
The magnification necessary for a flash occurs where a
line from the eye is tangential to the convex lower edge
of the inversion. If part of the layer has a stronger
curvature than that of the earth due to atmospheric waves
the flash can occur above the astronomical horizon.
Andrew Young adds: "The red rim where the Sun meets
the clouds is a nice example of [a coloured
rim]. If you are far enough from the apparent
horizon it will have a red line along it like this because
of dispersion in the intervening atmosphere. The general
raggedness of the solar limb here suggests that there
might be breaking Kelvin-Helmholtz waves on some of the
inversions."
Image ©2004 Tony Cook, reproduced with permission. |
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